Fork lift

ABSTRACT

A fork lift vehicle having a vertically movable fork powered upwardly and downwardly and adapted to be mounted on the rear of a truck provided with spaced longitudinal sockets for receiving the fork tines, the fork lift vehicle being capable of elevation and support by the truck by downward force applied on the fork after the tines are positioned in the sockets on the truck; the fork lift vehicle having a pair of forward wheels disposed laterally outwardly from the fork tines and being independently displaceable rearwardly to a point adjacent the rear of the fork prior to location of the tines in the sockets on the truck.

United States Patent Grether et a1.

FORK LIFT Mar. 26, 1974 Primary ExaminerAlbert J. Makay 5 7 ABSTRACT A fork lift vehicle having a vertically movable fork powered upwardly and downwardly and adapted to be mounted on the rear of a truck provided with spaced longitudinal sockets for receiving the fork tines, the fork lift vehicle being capable of elevation and support by the truck by downward force applied on the fork after the tines are positioned in the sockets on the truck; the fork lift vehicle having a pair of forward wheels disposed laterally outwardly from the fork tines and being independently displaceable rearwardly to a point adjacent the rear of the fork prior to location of the tines in the sockets on the truck.

[22] Filed: Jan. 26, 1973 [21] Appl. No.: 326,745

[52] US. Cl. 214/515, 187/9 [51] Int. Cl B60p 1/64 [58] Field of Search 214/515, 38 D, 75 R, 75 T; 187/9 [56] References Cited UNITED STATES PATENTS 3,390,797- 7/1968 Goodacre et a1. 214/515 3,695,471 10/1972 Rivers, Jr 214/515 FORK LIFT PRIOR ART Prior patents known to us are U.S. Pat. No. 2,966,275, granted to Brookins on Dec. 27, 1960, for Equipment Carrier, and US. Pat. No. 3,407,950, granted Oct. 29, 1968 to Ward for Means for Attaching a Lift Truckto a Lorry.

The invention has as a general object the provision of a powered fork lift truck, the fork tines of which can be positioned in elongated sockets carried by a motor truck and power applied to the fork, the power having a downward movement whereby the remainder of the fork lift vehicle is elevated to permit the fork lift vehicle to be transported by the motor truck with the fork lift vehicle out of contact with the road surface.

Another object of the invention is to provide a fork lift vehicle of the class described above with a pair of forward wheels which, in the normal operation of the fork lift, lie laterally outwardly with respect to the fork and its tines and wherein these forward wheels can be displaced rearwardly at least to a point adjacent the rear portion of the fork so that the tines can be freely inserted in the sockets on the motor truck without interference from saidforward wheels. It would be poor design to permanently locate the forward wheels adjacent the rear of the fork because it would greatly limit the load capacityfof the fork. Furthermore, with the forward wheels displaced on a transverse line approximately midway of the length of the fork tines, heavy loads can be handled without requiring a heavy counterweight on the rearward portion of the fork lift vehicle.

Another object of the invention is to provide a fork lift vehicle with rearwardly retractable forward wheels wherein one of the forward wheels can be retracted in truck loading operations where the retracted wheel, if left in its forward position, would interfere with a rear truck wheel and prevent proper maneuvering of the fork liftvehicle toa postion for despositing its load on the truck bed. I

Other objects and advantages of the invention will more fully appear from the following description in connection with the accompanying'drawings:

FIG. 1 'is a side elevational view of a fork lift vehicle embodying one form of the invention;

FIG. 2 is a front elevational view of the fork lift vehicle;

FIG. 3 is a horizontal sectional view taken approximately on'the line 3-3 of FIG. 1;

FIG. 4 is an enlarged detail taken th line 44 ofFIG. 3;

FIG. 5. is a horizontal longitudinal sectional view taken approximately on the line 5-5 of FIG. 4;

FIG. 61's an enlarged detail showing the right half of the structure in FIG. 5 with the sub-frame locking bolt in an alternate position;

FIG. 7 is a side elevational view of the fork lift vehicle with its forward wheel assembly shown in forwardly disposed and retracted positions in broken and full lines respectively, and showing the fork in brokdn and full lines to illustrate the manner in which the forward wheel assembly is elevated and retracted and the fork is positioned for reception in suitable sockets on the rear of the motor truck;

approximately on FIG. 8 is a side elevational view with portions broken away of the fork lift vehicle in its secured position for transportation in an elevated position by a motor truck;

FIG. 9 is a sectional view taken approximately on the line 9-9 of FIG. 8;

FIG. 10 is an enlarged detail of the manner in which the rear sub-frame for each forward wheel and auxiliary wheel is pivotally supported for retraction from its forward position;

FIG. 11 is a side elevational view of a fork lift vehicle showing a different form of retractable forward wheel structure;

FIG. 12 is a view of the structure in FIG. 11 with the forward wheels retracted and the fork lift vehicle supported at the end of a truck chassis.

The device of FIGS.- 1 through 10 includes a fork lift vehicle 14 having longitudinal frame side members 16 and one or more cross members, a forward cross member being shown at 18. A pair of vertical fork guide frames 20 extend upwardly from adjacent the forward cross frame member 18. Each vertical guide frame 20 is pivotally connected at 22 to one each of a pair of upwardly and rearwardly extending brackets 24 welded to the cross frame 18 as indicated at 26 in FIG. 2. The lower ends of the vertical guide frame members 20 are connected by a cross member 28. The vertical frame members are connected at vertically spaced points by cross members 30 and 32. Connected to the lower vertical frame cross member 28 as indicated at 34, is the lower end of a hydraulic cylinder 36 into which extends a piston rod 38 having the conventional piston not shown. The lower end of the cylinder 36 is positioned with a hydraulic line connection for the admission of pressurized hydraulic fluid beneath the piston and the cylinder 36 and an upper connection 42 is provided for pressurized hydraulic fluid which acts against the top of the piston in the cylinder 36. Thus, both the upward and downward strokes of the piston rod 38 are power strokes.

The upper ends of the piston rod 38 is connected to a cross piece 44 whose ends are suitably secured to the upper ends of a pair of spaced tubes 46 which as shown in FIG. 3, are provided with rollers 48 rotating in the vertical stationary frame members 20. Any suitable number of rollers 48 can be used at vertically spaced points along their respective tubes 46. Short forwardly disposed webs 50 connect the vertical tubes 46 with a pair of vertically spaced fork cross members 52 and 54. The outer endsof the fork cross members 52 and 54 are connected by plates 56 and to each plate is welded or otherwise suitably secured thereto a vertical portion 58 of a fork member 60, and each fork member also including a horizontal tine 62.

The cross piece 30 extending between the vertical frame members 20 is pivotally connected at 64 to a piston rod 66 extending into a hydraulic cylinder 68 whose left end is pivotally connected at 70 to the top 72 of a fork lift vehicle housing 74 within which is located a hydraulic pump and reservoir, all conventionally indicated by broken lines at 76, these being conventional parts of a fork lift mechanism. Supported by the housing 74 is a seat 78 and a steering wheel 80, and such other controls as are necessary to operate the fork lift vehicle. These controls are not shown because they also are conventional and well known in the art.

The cylinder and piston unit 68, 66 connected between the housing 74 and the vertical frame members 20 are used to tilt said frame members 20 and the fork mechanism so that the fork members 60 and their tines 62 can be tilted somewhat as necessary in the engagement and disengagement of articles, such as pallets, and also to permit the fork to be tilted rearwardly slightly when carrying a load which might otherwise tilt and fall forwardly from the fork. The rear of the fork lift vehicle is supported centrally in a transverse direction by a single rear wheel 82 which is connected by a chain 82 to a hydraulic motor 86, the latter being driven by the usual motor and main hydraulic pump. The manner in which the single rear wheel 82 is steered is also not illustrated since that mechanism is also quite conventional.

THE RETRACTABLE FORWARD WHEELS On each side of the forward portion of the fork lift vehicle is a wheel 90. Each wheel 90 is mounted on a stub axle 92 carrying a gear 94. A chain 96 drives the gear 94 from a driving gear 98 on a hydraulic wheel motor 100. The stub axle 92, the wheel motor 100 and the respective gears are all supported by a sub-frame 102 which is pivotally connected at 104 to the forward portion of its respective main frame side member 16.

The stub frame 102 as shown in FIG. has an offset rearward extension 106 which is mounted on the subframe pivot 104. The offset 106 is secured to the subframe 102 by welding indicated at 108 in FIG. 5 so that said sub-frame 102 and offset rearward extension 106 are in effect a single rigid structure. Mounted in the sub-frame offset 106 is a bearing 110 in which is a stub shaft 112 which carries on its outer end an auxiliary wheel 114.

When the sub-frame 102 is in its downward and forward position as illustrated in FIG. 5, a pin 116 which protrudes rearwardly. from the rear end of the main sub-frame 102 lies in a groove 118 in a forward end piece 120 in the main side frame 16. This pin and groove arrangement assists the sub-frame pivot 104 in securely holding the sub-frame in its forward position and against undue lateral shifting.

The forward side portion of the main frame 16 is provided with a hole 122 which matches a hole 124 in one side of the sub-frame rearward extension 106 and matches with a hole 126 in the outer side of the subframe extension. Said extension 106 has one end of a sleeve 128 welded thereto as shown in FIG. 5. Extending through sleeve 128 is a locking bolt 130 which extends through the holes 126 and 124 in the sub-frame extension and the coinciding hole 122 in the side of the forward portion of the main frame member 16. Within the sleeve 128 is a spring 132 whose outer or lower end as viewed in FIG. 5, is anchored in the sleeve 128. The inner or upper end of the spring is movable outwardly in the sleeve 128 with the bolt 130 by reason of a pin 134 which is mounted in the bolt 130 and engages a convolution of the spring. The bolt 130 extends outwardly of the sleeve 128 and is provided with a pull handle 136. It will be seen that when the handle 136 is pulled to pull the pin 130 from the hole 122 in the side of the forward end of the main frame, the sub-frame 102 and its rearward extension 106 can be swung upwardly and rearwardly relative to the main frame. In order to retain the bolt 130 in its retracted position, the

pin 134 has its outer end riding in a slot 138, said slot having an angled outer end in the manner of a bayonet slot so that when the bolt is retracted as staged above to the point where the pin 134 is at the outer end of the slot 138, a slight counterclockwise turn of the bolt handle 136 will lodge the pin in the angled end of the slot and releasably hold the bolt 130 in its retracted position. Referring to FIG. 7, the sub-frame 102 has been released through manipulation of the bolt 130 and swung from its roughly horizontal forwardly disposed position, indicated in broken lines, to an upwardly and somewhat rearwardly directed position shown in full lines. In order to accomplish this, the fork 60 must be lowered into contact with the ground and hydraulic force applied through the conduit 42 at the upper end of the vertical cylinder 36. This creates a downward push on the fork sufficient to elevate the forward portion of the fork lift vehicle and more particularly the forward wheels 90. The fork in this position is shown in broken lines in FIG. 7. As the sub-frame 102 and wheel 90 is swung upwardly about the pivot 104, the auxiliary wheel 114 will be swung downwardly in a counterclockwise direction until it engages the ground, or the fork can be forced downwardly to lift the vehicle slightly more than shown in FIG. 7 until the sub-frame 102 is swung to the full line position and then the fork raised sufficiently for the auxiliary wheel 114 to engage the ground in a vehicle supporting position. It will be noted that in this position illustrated in FIG. 7, the subframe 102 has been swung rearwardly over vertical dead center so that the weight of the fork lift vehicle on auxiliary wheels 1 14 will maintain the sub-frame 102 in its rearward over center position.

It will be seen that the wheels 90 in their retracted position are adjacent the rear of the fork 60 and more specifically are actually rearward of the fork construction. The auxiliary wheels lie in a vertical plane also adjacent the rear of the fork 60. This leaves the fork tines 62 extending forwardly of any, other portion of the fork lift vehicle. Therefore, the fork can be raised to the full line position of FIG. 7 with the tines 62 in alignment with tubular sockets 140 which are mounted on inverked U-shaped supports 142 and 144 which extend downwardly from the underside of the truck bed 146. When the tines 62 are aligned with the tubular sockets 140, the fork lift vehicle can be driven forwardly under power from the single rear wheel 82 and the tines run only into the sockets 140 as shown in FIG. 8. In this figure it will be seen that each socket 140 has an upward rear slotted portion 148 to receive a portion of the vertical fork member 58 to assist in preventing the fork elements from tilting in the sockets 140.

When the fork tines have been located in the sockets 140, power is applied to the fork to tend to move it in a downward direction. Since the fork tines are located in the sockets 140, the fork cannot move downwardly and the result is that the remainder of the fork lift vehicle is raised. This raised position is illustrated in FIG. 8.

In order to insure the retention of the fork tines 62 in the sockets 140 a winch 150 is mounted on each side of the rear end of the truck bed 146, the winch being rotated by a suitable handle 152 on the winch shaft 154. A ratchet 156 and a suitable pawl (the latter not shown) releasably secures the winch in the customary manner. A cable 158 on the winch has an eye 160 on its free end to permit the cable to be secured to a hook 163, there being one of each cable and hook and the hook being located on the rear portion of the main frame 16. In FIGS. 11 and 12 there is illustrated a modification wherein forward wheels 164 each carried by a horizontal square shaft 166 are slidable fore and aft in a square tubing 168 mounted on the side of a fork lift vehicle frame member 170. The forward end of the tube 168 terminates short of the forward end of the frame member 170 and the square shaft 166 which supports the wheel 164 is sufficiently long to permit said wheel 164 to be extended to a vertical plane which intersects the fork tines 62. Carried on top of the square tubeing 168 is a hydraulic cylinder 172 having pressure fluid connections 174 which alternately serve as inlets and outlets so that a piston (not shown) in the cylinder 172 and connected to a piston rod 176 can retract the wheel 164 or move it forwardly to the position of FIG. 11. When the wheel is retracted, it lies at the rear of the fork 60 so that the fork tines 62 can be inserted in their sockets 140 and the vehicle elevated to the position of FIG. 12 in the same manner as that described in connection with the preceding embodiment.

From the foregoing it will be seen that I have provided a fork lift vehicle which can be conveniently mounted upon the rear portion of amotor truckfor transportation without being required to tow the fork lift vehicle. It is provided with forward working wheels 90 and in the other embodiment 164, which wheels are located forwardly of the rear of the fork body andge'nerally midway between the front and rear of the horizonal tines. These wheels are sturdy enough to support the loads for which the fork lift vehicle was built. These wheels can be retracted and the fork lift vehicle supported by rearwardly disposed auxiliary wheels which need be strong enough only to support the unloaded fork lift vehicle. These auxiliary wheels permit maneuvering of the vehicle to a position where the fork tines are in an elevated position, aligned with the tinereceiving sockets carried'by the motor truck.

It is important to note-that in both embodiments of the invention it is possible to retract one of the forward pair of wheels so that thefork lift vehicle can maneuver close to the rear corner of the truck bed for unloading a loaded pallet or the like. While it is not possible to travel any distance with one of the forward wheelsretracted and a heavy load on the fork, the device is capable of displacing the load from the truck to the fork lift vehicle by extending the retracted wheel while removing the weight froman area on the truck bed where the truck wheels interfere with the front wheels of the fork .lift.

It will of course be understood that various changes can be made in the form, details, arrangement and proportions of the various parts without departing from the scope of our invention.

We claim:

l. A fork lift for use with a truck chassis having fort tine sockets thereon, wherein the improvement comprises: a powered fork lift vehicle having a frame assembly and a fork with a pair of generally horizontal tines, means on the vehicle and carrying said fork for raising and lowering the fork under power, the fork being located at the forward end of the vehicle, wheel means supporting the rear end of the vehicle, a pair of wheels at the forward end of the vehicle and positioned laterally outwardly of the fork, said fork lift vehicle having a main frame, forwardly extending sub-frame members carrying one "each of said pair of wheels, the wheels being on the forward ends of the sub-frame members, said sub-frame members each having a movable connection with the main frame rearwardly of said pair of wheels, and the sub-frame and wheels being movable from a main frame supporting position to a position rearwardly relative to the main frame and fork to permit the fork tines to be inserted in said sockets on the vehicle chassis and the fork lift vehicle raised by the application of lowering power to the fork.

2. The structure in claim 1, and each sub-frame having an auxiliary wheel thereon rearwardly of the subframe pivotal connection, said auxiliary wheels being held out of contact with the ground when said pair of wheels is in ground contact, and the auxiliary wheels being in fork lift frame supporting ground contact when said pair of wheels is retracted.

3. The structure in claim 1, and means carried by said vehicle frame supporting said pair of wheels for rectilinear movement from said positions laterally outwardly of the fork to positions adjacent the rear of the fork.

4. The structure in claim 1, and said vehicle having an upstanding fork guide, the fork being vertically movable on said guide, vertically movable double acting power means on said vehicle and connected to said fork to raise and lower said fork, and said fork being movable downwardly under power to a position to engage the ground and raise said pair of wheels from the ground to support the forward end of the vehicle, and to permit the sub-frames and said pair of wheels to be retracted.

5. The structure in claim 4, and each sub-frame having an auxiliary wheel theron rearwardly of the subframe pivotal connection, the auxiliary wheels being suspended above ground when said pair of wheels is in fork lift supporting ground contact, and when the fork is moved downwardly to engage the ground and raise said pair of wheels and the pair of wheels is retracted, the auxiliary wheels engage the ground adjacent the rear of the fork.

6. The structure in claim 1, and means releasably locking each sub-frame to the main frame when said pair of wheels arein their main frame supporting position.

7. The structure in'claim l, and means releasably interconnecting the sub-frame and the main frame when the sub-frames and said pair of wheels are in their main frame supporting position.

8. The structure in claim 1, and winch and cable means for connection between the fork lift vehicle and a truck chassis upon which the fork lift vehicle is mounted to prevent dislodgment of the fork tines from said sockets.

9. The structure in claim 1, and tie means for connection between the fork lift vehicle and a truck chassis upon which the fork lift vehicle is mounted with the fork tines in said sockets, to prevent dislodgment of the fork tines from said sockets.

10. The structure in claim 3, and a double-acting piston and cylinder unit supported adjacent and parallel to said means for supporting the pair of wheels for rectilinear movement so that the path of travel of the piston and cylinder unit is parallel to the path of travel of one of said pair of wheels.

11. The structure in claim 10, and independently actuated piston and cylinder units adjustable to product 3,799,379 7 8 independent retraction and extension of the left and change the distance between the rear and front wheels right forward wheels. and consequently change the weight displacement on 12. The structure in claim 10, and simultaneously acthe forward wheels. tuable piston and cylinder units linearly adjustable to 

1. A fork lift for use with a truck chassis having fort tine sockets thereon, wherein the improvement comprises: a powered fork lift vehicle having a frame assembly and a fork with a pair of generally horizontal tines, means on the vehicle and carrying said fork for raising and lowering the fork under power, the fork being located at the forward end of the vehicle, wheel means supporting the rear end of the vehicle, a pair of wheels at the forward end of the vehicle and positioned laterally outwardly of the fork, said fork lift vehicle having a main frame, forwardly extending sub-frame members carrying one each of said pair of wheels, the wheels being on the forward ends of the sub-frame members, said sub-frame members each having a movable connection with the main frame rearwardly of said pair of wheels, and the sub-frame and wheels being movable from a main frame supporting position to a position rearwardly relative to the main frame and fork to permit the fork tines to be inserted in said sockets on the vehicle chassis and the fork lift vehicle raised by the application of lowering power to the fork.
 2. The structure in claim 1, and each sub-frame having an auxiliary wheel thereon rearwardly of the sub-frame pivotal connection, said auxiliary wheels being held out of contact with the ground when said pair of wheels is in ground contact, and the auxiliary wheels being in fork lift frame supporting ground contact when said pair of wheels is retracted.
 3. The structure in claim 1, and means carried by said vehicle frame supporting said pair of wheels for rectilinear movement from said positions laterally outwardly of the fork to positions adjacent the rear of the fork.
 4. The structure in claim 1, and said vehicle having an upstanding fork guide, the fork being vertically movable on said guide, vertically movable double acting power means on said vehicle and connected to said fork to raise and lower said fork, and said fork being movable downwardly under power to a position to engage the ground and raise said pair of wheels from the ground to support the forward end of the vehicle, and to permit the sub-frames and said pair of wheels to be retracted.
 5. The structure in claim 4, and each sub-frame having an auxiliary wheel theron rearwardly of the sub-frame pivotal connection, the auxiliary wheels being suspended above ground when said pair of wheels is in fork lift supporting ground contact, and when the fork is moved downwardly to engage the ground and raise said pair of wheels and the pair of wheels iS retracted, the auxiliary wheels engage the ground adjacent the rear of the fork.
 6. The structure in claim 1, and means releasably locking each sub-frame to the main frame when said pair of wheels are in their main frame supporting position.
 7. The structure in claim 1, and means releasably interconnecting the sub-frame and the main frame when the sub-frames and said pair of wheels are in their main frame supporting position.
 8. The structure in claim 1, and winch and cable means for connection between the fork lift vehicle and a truck chassis upon which the fork lift vehicle is mounted to prevent dislodgment of the fork tines from said sockets.
 9. The structure in claim 1, and tie means for connection between the fork lift vehicle and a truck chassis upon which the fork lift vehicle is mounted with the fork tines in said sockets, to prevent dislodgment of the fork tines from said sockets.
 10. The structure in claim 3, and a double-acting piston and cylinder unit supported adjacent and parallel to said means for supporting the pair of wheels for rectilinear movement so that the path of travel of the piston and cylinder unit is parallel to the path of travel of one of said pair of wheels.
 11. The structure in claim 10, and independently actuated piston and cylinder units adjustable to product independent retraction and extension of the left and right forward wheels.
 12. The structure in claim 10, and simultaneously actuable piston and cylinder units linearly adjustable to change the distance between the rear and front wheels and consequently change the weight displacement on the forward wheels. 